It is known that the wavelength of laser light emitted from a semiconductor laser element depends on the temperature of the semiconductor laser element. As an example, in a lighting apparatus having a semiconductor laser element, there is a problem that if the wavelength of the laser light changes, the color of the laser light changes. Thus, in order to suppress a variation of the wavelength of the laser light, it is required to maintain the temperature of the semiconductor laser element within a desired range.
From such a viewpoint, the laser light source device of Patent Document 1 includes a cooler that cools a semiconductor laser element, and controls the cooler such that the temperature of the semiconductor laser element reaches a preset temperature. More specifically, in the laser light source device of Patent Document 1, the element temperature of the semiconductor laser element is measured, and when the element temperature is higher than the preset temperature, a current value flowing through the cooler is increased, and when the element temperature is lower than the preset temperature, the current value flowing through the cooler is decreased.